The objectives of the proposed research are to study the mechanism and regulation of neurotransmitter biosynthesis in the mammalian central nervous system. The initial efforts are directed toward the isolation and purification of (1) choline acetyltransferase and (2) glutamate decarboxylase which catalyze the biosynthesis of acetylcholine and gamma-aminobutryic acid (GABA), respectively. Classical enzyme fractionation techniques and affinity chromatography will be used. The second phase of the study is directed toward the elucidation of the mechanism of enzyme action. Isotope exchange, isolation of enzyme intermediates, and active site sequence determination are planned avenues of study. The effects of several biochemical parameters on the enzyme activity will be explored. These include possible acetylation and phosphorylation of the choline acetyltransferase and ionic effects on glutamate decarboxylase. These studies are relevant to disease states which may be associated with increased or decreased neuronal activity including seizure disorders and Parkinsonism.